mysqli oop return null

Question

Can somebody tell me what went wrong with my code :

class sub_category
{
    private $con;
    function __construct()
    {
        $this->con = new mysqli("localhost", "root", "", "whatever");
    }

    function show_all()
    {
        $per_page=5;
        if(isset($_GET['page']))
        {
            $page = $_GET['page'];
        }
        else
        {
            $page = 1;
        }

        $start_from = ($page-1)*$per_page;

        $sql = "SELECT sub_kategori.id_sub_kategori, kategori.nama_kategori, sub_kategori.nama_sub_kategori FROM sub_kategori INNER JOIN kategori ON kategori.id_kategori = sub_kategori.id_kategori ORDER BY sub_kategori.id_sub_kategori LIMIT ?, ?";
        $stmt = $this->con->prepare($sql);
        $stmt->bind_param('ii', $start_from, $per_page);
        $stmt->execute();
        $stmt->bind_result($id, $namecat, $cat);
        while($stmt->fetch())
        {
            echo "<tr>";
            echo "<td>$id</td>";
            echo "<td>$namecat</td>";
            echo "<td>$cat</td>";
            echo "<td><a href='javascript:'>Update</a></td>";
            echo "<td><a href='sub_category.php?ghgfh=$id'>Delete</a></td>";
            echo "<td><a href=''>Report</a></td>";
            echo "</tr>";
        };
        $stmt->close();
        $page_sql = "SELECT sub_kategori.id_sub_kategori, kategori.nama_kategori, sub_kategori.nama_sub_kategori FROM sub_kategori INNER JOIN kategori ON kategori.id_kategori = sub_kategori.id_kategori ORDER BY sub_kategori.id_sub_kategori";
        $stmt_page = $this->con->query($page_sql);
        $total_record = $stmt_page->num_rows;
        $total_page = ceil($total_record/$per_page);
        echo "</tbody>";
        echo "</table>";
        echo "<center>";
        echo "<ul class='pagination'>";
        echo "<li><a href=sub_category.php?page=1>First Page</a></li>";
        for($i=1;$i<=$total_page;$i++)
        {
            if(isset($_GET['page']))
            {
                if($i==$_GET['page'])
                {   
                    echo "<li class='active'><a href=sub_category.php?page=$i>$i</a></li>";
                }
                else
                {
                    echo "<li><a href=sub_category.php?page=$i>$i</a></li>";
                }
            }
            else
            {
                echo "<li><a href=sub_category.php?page=$i>$i</a></li>";
            }
        }
        echo "<li><a href=sub_category.php?page=$total_page>Last Page</a></li>";
        echo "</ul>";
        echo "</center>";
        $stmt_page->close();
    }

    function show($nama_sub_kategori)
    {

        $per_page=5;
        if(isset($_GET['page']))
        {
            $page = $_GET['page'];
        }
        else
        {
            $page = 1;
        }

        $start_from = ($page-1)*$per_page;

        $nama_sub_kategori = "%$nama_sub_kategori%";
        $sql = "SELECT sub_kategori.id_sub_kategori, kategori.nama_kategori, sub_kategori.nama_sub_kategori FROM sub_kategori INNER JOIN kategori ON kategori.id_kategori = sub_kategori.id_kategori WHERE sub_kategori.id_sub_kategori LIKE ? OR sub_kategori.nama_sub_kategori LIKE ? OR kategori.nama_kategori LIKE ? ORDER BY sub_kategori.id_sub_kategori LIMIT ?, ?";
        $stmt = $this->con->prepare($sql);
        $stmt->bind_param('sssii', $nama_sub_kategori, $nama_sub_kategori, $nama_sub_kategori, $start_from, $per_page);
        $stmt->execute();
        $stmt->bind_result($id, $namecat, $cat);
        while($stmt->fetch())
        {
            echo "<tr>";
            echo "<td>$id</td>";
            echo "<td>$namecat</td>";
            echo "<td>$cat</td>";
            echo "<td><a href=''>Update</a></td>";
            echo "<td><a href='sub_category.php?ghgfh=$id'>Delete</a></td>";
            echo "<td><a href=''>Report</a></td>";
            echo "</tr>";
        };
        $stmt->close();
        $page_sql = "SELECT count(*) as total FROM sub_kategori INNER JOIN kategori ON kategori.id_kategori = sub_kategori.id_kategori WHERE sub_kategori.id_sub_kategori LIKE ? OR sub_kategori.nama_sub_kategori LIKE ? OR kategori.nama_kategori LIKE ? ORDER BY sub_kategori.id_sub_kategori";
        $stmt_page = $this->con->prepare($page_sql);
        $stmt_page->bind_param('sss', $nama_sub_kategori, $nama_sub_kategori, $nama_sub_kategori);
        $stmt_page->execute();
        $stmt_page->bind_result($row);
        $total_record = $row;
        echo $total_record;
        $total_page = ceil($total_record/$per_page);
        echo "</tbody>";
        echo "</table>";
        echo "<center>";
        echo "<ul class='pagination'>";
        echo "<li><a href=sub_category.php?page=1>First Page</a></li>";
        for($i=1;$i<=$total_page;$i++)
        {
            if(isset($_GET['page']))
            {
                if($i==$_GET['page'])
                {   
                    echo "<li class='active'><a href=sub_category.php?page=$i>$i</a></li>";
                }
                else
                {
                    echo "<li><a href=sub_category.php?page=$i>$i</a></li>";
                }
            }
            else
            {
                echo "<li><a href=sub_category.php?page=$i>$i</a></li>";
            }
        }
        echo "<li><a href=sub_category.php?page=$total_page>Last Page</a></li>";
        echo "</ul>";
        echo "</center>";
        $stmt_page->close();
    }
 }

The show_all() function is working perfectly fine ! it show data and pagination with no problem !

The show() function show me data it's working too ! but the pagination gave me NULL result !

I mean the

echo $total record;

It gave me null pagination ! is there something wrong with my code ?

Change $stmt_page = $this->con->prepare($page_sql); to $stmt_page = $con->prepare($page_sql); — Nana Partykar
– Nana Partykar, Commented Dec 16, 2015 at 19:23
Nope, it gave me error now :( Notice: Undefined variable: con in C:\xampp\htdocs\whatever\login\admin\sql\sub_category.php on line 108 Fatal error: Cannot access empty property in C:\xampp\htdocs\whatever\login\admin\sql\sub_category.php on line 108 — user2977799
– user2977799, Commented Dec 16, 2015 at 19:25
It inside class by the way and i put my $con variable inside construct function, it's working on other function but not on this one :( — user2977799
– user2977799, Commented Dec 16, 2015 at 19:27
If you want a function to return something use return not echo. — frz3993
– frz3993, Commented Dec 16, 2015 at 19:27
No, sorry, I don't want to return any value, just want to show it. — user2977799
– user2977799, Commented Dec 16, 2015 at 19:28

Pablo Digiani · Accepted Answer · 2015-12-16 19:31:13Z

1

Add a name (for example total) to the column:

 SELECT count(*) as total FROM sub_kategori ....

And then just echo the value:

echo $row->total

answered Dec 16, 2015 at 19:31

Pablo Digiani

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1 Comment

Pablo Digiani Over a year ago

Do a var_dump($row) before the echo, and tell me what it prints.

Bob Dill · Accepted Answer · 2015-12-16 20:10:20Z

1

Perhaps I'm missing something obvious in that I haven't used the $this in this way in php; that is, to specify access to a global variable outside a specific class. When sharing variables across functions, $global is used to specify the shared (con in this case) variable.
In your showAll function, you set $total_record = $stmt_page->num_rows; in your second (show) function you set $total_record = $row; where $row does not appear to have been initialized ... hence NULL is correct.

edited Dec 16, 2015 at 20:10

answered Dec 16, 2015 at 19:50

Bob Dill

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4 Comments

user2977799 Over a year ago

No it's not like that. I write it only "$row" because i already bind the result of "count(*)" from the query on "$row" variable, it's how mysqli bind result works in taking value from the executed query.

user2977799 Over a year ago

I use "count(*)" and bind_result because bind_param in mysqli not support num_rows.

Bob Dill Over a year ago

Right, so in your example (thanks for highlghting the bind), $row is bound to the resultset. So to get the number of rows, wouldn't you want to use $row->num_rows instead of just $row?

user2977799 Over a year ago

bind_param in mysqli not support num_rows, that's why i have to use "count(*)" and bind_result.

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